Commit 6cd735f0 authored by Benjamin Tissoires's avatar Benjamin Tissoires
Browse files

HID: bpf: protect HID-BPF prog_list access by a SRCU 

We want to add sleepable callbacks for hid_hw_raw_request() and
hid_hw_output_report(), but we can not use a plain RCU for those.

Prepare for a SRCU so we can extend HID-BPF.

This changes a little bit how hid_bpf_device_init() behaves, as it may
now fail, so there is a tiny hid-core.c change to accommodate for this.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-3-cfd60fb6c79f@kernel.org


Acked-by: default avatarJiri Kosina <jkosina@suse.com>
Signed-off-by: default avatarBenjamin Tissoires <bentiss@kernel.org>
parent 67eccf15

drivers/hid/bpf/hid_bpf_dispatch.c

+5 −1
Original line number Diff line number Diff line
@@ -506,13 +506,17 @@ void hid_bpf_destroy_device(struct hid_device *hdev) 
	hdev->bpf.destroyed = true;



	__hid_bpf_ops_destroy_device(hdev);



	synchronize_srcu(&hdev->bpf.srcu);

	cleanup_srcu_struct(&hdev->bpf.srcu);

}

EXPORT_SYMBOL_GPL(hid_bpf_destroy_device);



void hid_bpf_device_init(struct hid_device *hdev)

int hid_bpf_device_init(struct hid_device *hdev)

{

	INIT_LIST_HEAD(&hdev->bpf.prog_list);

	mutex_init(&hdev->bpf.prog_list_lock);

	return init_srcu_struct(&hdev->bpf.srcu);

}

EXPORT_SYMBOL_GPL(hid_bpf_device_init);

drivers/hid/bpf/hid_bpf_struct_ops.c

+2 −0
Original line number Diff line number Diff line
@@ -214,6 +214,7 @@ static int hid_bpf_reg(void *kdata) 
		list_add_rcu(&ops->list, &hdev->bpf.prog_list);

	else

		list_add_tail_rcu(&ops->list, &hdev->bpf.prog_list);

	synchronize_srcu(&hdev->bpf.srcu);



out_unlock:

	mutex_unlock(&hdev->bpf.prog_list_lock);
@@ -244,6 +245,7 @@ static void hid_bpf_unreg(void *kdata) 
	mutex_lock(&hdev->bpf.prog_list_lock);



	list_del_rcu(&ops->list);

	synchronize_srcu(&hdev->bpf.srcu);



	reconnect = hdev->bpf.rdesc_ops == ops;

	if (reconnect)

drivers/hid/hid-core.c

+7 −1
Original line number Diff line number Diff line
@@ -2875,9 +2875,15 @@ struct hid_device *hid_allocate_device(void) 
	mutex_init(&hdev->ll_open_lock);

	kref_init(&hdev->ref);



	hid_bpf_device_init(hdev);

	ret = hid_bpf_device_init(hdev);

	if (ret)

		goto out_err;



	return hdev;



out_err:

	hid_destroy_device(hdev);

	return ERR_PTR(ret);

}

EXPORT_SYMBOL_GPL(hid_allocate_device);

include/linux/hid_bpf.h

+4 −2
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 


#include <linux/bpf.h>

#include <linux/mutex.h>

#include <linux/srcu.h>

#include <uapi/linux/hid.h>



struct hid_device;
@@ -145,6 +146,7 @@ struct hid_bpf { 
	struct hid_bpf_ops *rdesc_ops;

	struct list_head prog_list;

	struct mutex prog_list_lock;	/* protects prog_list update */

	struct srcu_struct srcu;	/* protects prog_list read-only access */

};



#ifdef CONFIG_HID_BPF
@@ -153,7 +155,7 @@ u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type t 
int hid_bpf_connect_device(struct hid_device *hdev);

void hid_bpf_disconnect_device(struct hid_device *hdev);

void hid_bpf_destroy_device(struct hid_device *hid);

void hid_bpf_device_init(struct hid_device *hid);

int hid_bpf_device_init(struct hid_device *hid);

u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size);

#else /* CONFIG_HID_BPF */

static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
@@ -162,7 +164,7 @@ static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid 
static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }

static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}

static inline void hid_bpf_destroy_device(struct hid_device *hid) {}

static inline void hid_bpf_device_init(struct hid_device *hid) {}

static inline int hid_bpf_device_init(struct hid_device *hid) { return 0; }

#define call_hid_bpf_rdesc_fixup(_hdev, _rdesc, _size)	\

		((u8 *)kmemdup(_rdesc, *(_size), GFP_KERNEL))